Form rolling die, mounting construction therefor and method of manufacture and use



2,9925 73 D METHOD D. H. PRUTTON MOUNTING CONSTRUCTION THEREFOR AN OF MANUFACTURE AND USE July 18, 1961 FORM ROLLING DIE Filed July 16, 1957 2 Sheets-Sheet 1 INVENTOR.

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y 18, 1961 D. H. PRUTTON 2,992,573

FORM ROLLING DIE, MOUNTING CONSTRUCTION THEREFOR AND METHOD OF MANUFACTURE AND USE Filed July 16. 1957 2 Sheets-Sheet 2 INVENTOR. DAN/5L H. PEUTTOA/ United States Patent 9 2,992,573 FORM ROLLING DIE, MOUNTING CONSTRUC- TION THEREFOR AND METHOD OF MANUFAC- TURE AND USE 1 Daniel H. Prutton, 5305 W. 130th St., Cleveland 30, Ohio Filed July 16, 1957, Ser. No. 672,169 1 Claim. (Cl. 80-7) This invention relates to improvements in a threading die, mounting construction therefor, and/or method of manufacture and use.

One of the objects in the present invention is to provide Another object of the present invention is to provide a form rolling die and mounting construction thereof and/ or-method of manufacture and use of a die wherein no finish machining of the die, such as grinding, is required after heat treatment.

' A further object of the present invention is to provide a form rolling die mounting construction for easily assemblingor disassembling a die to a machine member in accurate alignment with a coacting form rolling die.

N A further object of the present inventionis to provide a form rolling die and mounting construction therefor and/or method of manufacture and use of a form-rolling die characterized by structural simplicity, economy of manufacture, ease of assembly of the component parts,

long die wear life, and/ or accurate die alignment.

Other features of this invention reside in the arrange ment. and design of the parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set claim.

In the drawings, 'FIG. 1 is a top plan view of a thread form rolling machine; i

forth in the appended FIG. 2 is a vertical, longitudinal sectional view taken along the line 2-2 of FIG. 1; r it FIG. 3 is a side elevational view of the die ring removed from said machine showing the axial distortion thereof; while FIG. 4 is a top plan view of the die ring removed from the machine showing the radial distortion thereof.

' Before the form-rolling die, mounting construction therefor, and/ or method of manufacture and use thereof here illustrated and disclosed is specifically described, it

isto beunderstood thatthe invention here involvedis not limited to the structural details, arrangementof parts, or method steps here disclosed, since machines or methods embodying the. present invention may take various forms. It also is to be understood that the phraseology or terminology herein employed is for purposes of de- 1 scription and not of limitation since the scope of the present invention is denoted by the appended claim.

While this invention might be adapted to various types of; machines, it has been chosento show the same as applied ,to a planetary type thread rolling machine of, the

samanrway ta e an s tab qman n j th ea 4 Outer 'die 14 has ice for rollingany suitable form on workpieces having generally cylindrical surfaces, such as on workpieces 10. Also, some aspects of this invention apply not only to die rings but alsoto platen type form rolling dies.

In this machine, a die ring 11 is mounted for rotation about a vertical axis. This die ring has a cylindrical bore 11;: providing an innerzone or group of cylindrically arranged surface portions of uniform diameter in the axial direction, has a cylindrical peripheral surface 11b forming an outer zone or group of cylindrically arranged surface portions of uniform diameter in the axial direction, has form rolling die contour surface portions on the peripheral surface 11b arranged generally cylindrically and equal distance from the axis of rotation of axis A, and has an end surface comprising a third zone or group of surface portions extending generally transversely to axis A and to the bore and peripheral surfaces 11a and 11b. The bore and peripheral sur-faces 11a and 11b, and the surface portions thereof, are arranged so that the inner and outer group of surface portions are coaxial and concentric in the mounted position illustrated in FIGS. 1 and 2. Although each of the groups or zones of surface portions 11a, 11b and 11c is continuous and forms a smooth surface, any of these may be made up of a plurality of surface portions having gaps therebetween, such as the peripheral or thread rolling surface in the aforementioned copending application corresponding to the peripheral surface 11b in the present application.

The form rolling die contour surface portions on peripheral surface 11b for the thread rolling purposes disclosed in the present application comprise a helical set of crests and grooves equal in pitch andother significant dimensions with the thread to be formed on the workpiece or thread rolling blank 10. The depth of. thread on blank 10 has been exaggerated in FIGQI to show the structure more clearly.

Cooperating with these form rolling die contour surface portions on peripheral surface 11b, which may sometimes for convenience be referred to hereinafter as being on a movable die or the inner die 11, is the stationary or first machine member 12 having outer or fixed dies 14. This stationary member 12 has a stationary table 13 having dies 14 adjustably secured to the top thereof in diametrically disposed relationship and having inner vertical concave'faces machined to be generally complementary "to the outer convex surface 11b of the inner die 11. Since each outer die and its securement structure to the table 13 is generally similar, only one will be described, for the other has the same reference numerals attached thereto. r t

aform rolling die contour portion 14a thereon having for rolling the threads disclosediherein a helical set of crests and grooves equal in pitch and other significant dimensions with the threads to be formed on the blankslll; the form rolling die contour 14a is ar- .stationary dies located in a common plane extending gen- .erally transverse tothe axis A, as shown in FIG. 2. However, the die contour portions 14a are not truly cylindrical with respect to axis A but instead have a modified radius of curvature, and are cocked slightly so that the spacing ,between the die contour portions 11b and 14a at the point of entry corner 14b of the blank 10 is just wide enough to accept and frictionally retain the blank or workpiece 10 and so that at the ejection corner of the blank or workpiece 10 the dies are close enough to have formed the thread desired as the die ring ll isrotated in the clockwise direction in FIG. 1. The difference in the gap be tween thesecorners isemphasized slightly inFIG. 1 for clarity. 1i

p r m detachably. interiits at 15 with the die holding .a combination of the two type distortions. contour portions and die ring surface 11b must be con- 3 block 16 and at a with a clamp finger 17 applied by means of a bolt 18, as best seen in FIG. 1. Vertical displacement of die 14 is prevented by a clamping bridge 19 retained on block 16 by bolt 20 and pressing the die '14 down against the top of stationary table 13 in definite locating position. The bridge 19 is slidable endwise, if desired, as permitted by a slot 21 through which the shank of bolt 20 passes.' The bolt, of course, must be slacked oif to permit endwise movement of the bridge 19. Thus, die 14 may be removed and another for rolling the same or different pitch threads or for rolling other type forms, replaced without removal of block 16. The block 16 is retained on table 13 by bolts 22 with the shanks of the bolts having limited clearance from the walls of the aperturm in block 16 through which they pass to permit minor adjustment of block and die positions before finally tightening bolts 22. A backstop block 24 is attached to the table 13 by bolts 26, and is horizontally pierced by threaded abutment bolts 27, which are advanced from several angles to serve in withstanding the stresses from the threading operation and in effecting positional adjustment of the die holding block 16 before bolts 22 are tightened down.

A second or rotatable machine member 30 is provided as a spindle or die ring base having a flange 31 with a base planar surface 31a for the die ring 11 with said surface extending transverse to the axis and having a base tapered peripheral surface 32 formed integrally there- 'with and concentric with the axis A.

'a start on form rolling die contour surface 11b rotates I into registry with a start on the die contour surface 14a,

:a blank or workpiece 10 will be introduced by this feeding means between the die contour portions at entry corner 14b. Continued rotation of the die ring 11 will grip the blank or workpiece 10 between the die contour portions and roll the blank clockwise in FIG. 1, will simultaneously thread the periphery of the blank, and

will eject the blank at the moment a blank passes the trailing or ejection corner 140. Hence, this rotational movement cause relative movement along the path of the'die contour portions 11b and 14a and will cause the coaction between them to form, roll the threads on the workpieces or blanks lfl'.

The present invention is directed primarily, to the manufacture and mounting of the die ring 11 carried by the spindle member 30. In good die design, whether the die be a ring or platen type die, it is desirable, that the metal of which it is composedbe easy, ,to machine, hard and tough on the form rolling die contour portions for long wear life, and have accurate threads or other forms thereon accurately coacting with form rolling die contour portions 14a on the stationary dies 14. However, if the die contour surface portions are machined when soft, and then heat treated :to harden, one will get a tough and hard heat treated surface on the die contour portion, which is capable of long wear, but the die will be distorted in heat treatment from a non-distorted shape with its accurate machining to a distorted shape after heat treatment.

sometimes of a radial distortion shown in FIG. 4, or of Since the-die centric with the. axis A, be in a plane transverse to the axis of rotation A, and be coplanar with the stationary die contour portions 14a, this distorted die cannot be This heat treat'distortion I takes the form of an axial distortion shown in FIG. -3, i

used in its distorted shape but its die contour portions or threads must be ground and its locating surfaces, shown herein as die surfaces 11a and 110, must be accurately ground after heat treatment so that it may be properly mounted and will properly coact with the stationary die contour portions 14a. However, this grinding will remove the hard and tough heat treated surface of the die contour portions 11b so as to reduce the die wear life.

The present invention eliminates the grinding operation on the die contour portions and the locating surfaces after heat treatment, retains the heat treated, tough and hard surface on the die contour portions 11b, and restores the die ring 11 to non-distorted shape after heat treatment for proper coaction with the stationary die contour portion 14a.

Here, die ring 11 is manufactured by the following method from any suitable material but preferably from an air hardening tool steel, such as SAE tool steel A1 or D2. First, bore and peripheral surfaces 11a and 11b are formed so that their respective groups of surface portions are arranged concentric, coaxial and cylindrical with respect to axis A. Then, end surface 11c is formed so that its third group of surface portions are planar'and transverse to axis A. Second, threads or other form rolling die contours are formed on peripheral surface 1111 so that its die contour portions are arranged concentric with the groupv of surface portions forming bore 11a. Although any method of forming these surface and die contour portions may be used, it is preferred that they be machined by single point or form cutting tools. Now, we have a die ring 11 of non-distorted shape with its die contour portions and mounting surface portions being accurately formed or machined to properly coact with die contour portions 14a 11. mounted coaxially on spindle member 30. Third, die ring 11 is heat treated so that its form rolling die portions 11b will be hardened and have a heat treated surface formed thereon for toughness and hardness to provide a long die wear life. This heat treatment may take any suitable form but preferably the heat treatment .of the tool steel of the die is performed by heating the die above the critical temperature in a vapo-carb atmosphere to hardening temperature and then quenching at least the die portions 11b to harden them in any suitable fluid, such as by a blast of air. However, during heat treating, the die ring will be warped to a distorted shape .with this distortion taking the form of a non-planar or axial type distortion shown in FIG. 3 (the parallel and planar opposite top and bottom edges now form a parallel vertical waive); the radial type distortion in FIG. 4, described as being wavey out of round; or a combination of these two type distortions. Quencing by an air blast, although providing more distortion than still air, provides a harder surface 11b, which may be drawn to a lower hardness, if preferred. a

The spindle or second member 30 includes means (1) for mounting the die ring 11 on member 30 for. rotation therewith, (2) for restoring the die ring 11 from distorted to non-distorted shape, and (3) for aligning'the form rolling die contour portions 11b of die ring 11 with the form rolling die contour portions 14a with the contour portions located in transversely coplanar and equally spaced or generally concentric relationship with axis A so that all die contour portions properly coact for rolling contours on workpieces or blanks 10. This operation is performed by applying the desired forces to the two locatiing surfaces 11a and of the'die ring 11 to properly locate and grip it. An expanding force is applied on the inner group of surface portions 11a to eliminate cylindrical distortion, as shown inFIG. .4, and to fix-die ring -11 to the second member 30 with the die contour portions 11a generally concentric with axis A. Also, an axialforce issimultaneously applied to ring 11 to urge'or pull the third or other mounting group of surface portions 110 down again st the base planar surfacefila to eliminate axial distortion of the type shown in FIG. 3.

The shape restoring, aligning and mounting means includes the base tapered surface 32, here shown as a beripheral surface on spindle 30 concentriewith axis Aand a plurality of segments 35 of a ring, here shown'as four in number, forming expanding shoes having concentric complementary-taperedinner surfaces 35f and cylindrical outer surface 35g with these surfaces coaxial and'coacting respectively with the base tapered peripheral surface 32 and the inner group of ring surface portions 11a. These segmentss35 may be. manufacturedbymachining a ring to the desired shape, hardening it, grinding it and radially cutting the ring into segments by a slot-cutting abrasive wheel.

This shape restoring, mounting and aligning means includes means for axially advancing segments 35 over the tapered peripheral surface 32 and for advancing the group of die ring surface portions 11c against the planar surface 31a so that the base tapered surface 32 exerts an outward radial centering and gripping force against the inner group of surface portions 11a on the die ring, while segments 35 push die 11 axially against surface 31a so that the base planar surface 31a axially locates die ring 11 in coplanar relationship with outer dies 14 in the manner shown in FIG. 2. In the present disclosure, this axial advancing means is disclosed as two symmetrically arranged screws 36 for each segment 35 having their longitudinal axes arranged parallel to the axis A and located in aligned holes 35a and 31b respectively in the segment '35 and the flange 31. Each screw 36 has its threaded portion screwed into one element, here shown as hole 31b and has its head engaging in a connterbore of the other element, here shown as conterbore 35b, remote from the first element, namely, the flange 31. However, it should be readily understood that the threaded hole and the counterbored hole may be reversed in FIG. 2. so that the counterbored hole is in flange 31 and the threaded hole is in the segment 35. However, the illustrated form is preferred because of the convenience in assembly since the socket heads of screws 36 are easily reached from the open top of the machine.

Now, it should be apparent that turning screws 36 to advance the segments 35 in the downward direction in FIG. 2. will mount the die ring 11 on the spindle member 30 to grip it for rotation therewith, will align the die contour portions 11b in spaced relationship and spaced radial relationship with die contour portions 14a and will align these die contour portions axially in transversely aligned coplanar relationship for proper coaction for rolling the thread form on the periphery of the workpiece or blank and will restore the die ring 1 1 from the distorted to the non-distorted shape for proper thread rolling action by applying radial expanding and axial locating forces to the die ring 11. The die ring 11 is easily restored to the non-distorted position because it is a thin-walled ring, thin enough to be stretched round to the non-distorted shape. For example, it has been found that a ring having a inch radial thickness with a 10 /2 inch internal diameter of surface 11a will be easily distorted in this manner with the radial distortion removed by uniformly expanding the die and the axial distortion removed by pulling the die against the locating surface 31 into coplanar relationship. The thread rolling die contours 14a and 11b will be properly aligned for proper coaction.

Since the die ring 11 must be sprung to some degree to lock it to the spindle 30 in the FIG. 2 position, removal of the screws 35 may not cause upward movement of the segments 35 in FIG. 2, so that means is preferably provided for advancing the segments 35 in the upward or opposite direction. Here, each segment 35 has two symmetrically arranged threaded holes 35 extending generally parallel to the axis A to receiver puller or jack-up screws bearing against the top surface 31a of flange 31 so that as the jack-up screws are advanced downwardly by rotation, they will pull the segments 35 off the base tapered 6 peripheral surface-32 and will; pullthe die ring 11 Tofitlie spindlemember 3.0. 1 1 "Ihe advantages for this construction are readily ap: preciated; First, vno finish. grinding of the form, rolling die contour portions on surface 1-1b, the inner group of locatging surface portions 11a, and/ or the lower group of locating or mountingijsilrface portions is. required after heat treatment. Second, segments-35, and-the construction associated therewith, eliminate distortion in the heat treated die ring B1 so that its peripheral die contour portions are generally-concentric with aild coplanar withthe die contour portions -14a-- for proper rolling coaction. Third, a hard and tough heat treated surface is retained on the die contour portions 11b since no finish grinding is required. It is the hardest at the outer extreme surfaces of the die contour surface to provide a hard and tough surface for long die life. Fourth, the small radial dimension or thin-walled dimension of the die ring 11 permits the tool die ring 11 to be made of less of the expensive tool material of which it is composed so that the die ring can be manufactured with minimum expense. It should be readily understood that many variations come within the scope of this invention. Many aspects of this invention readily apply to other type or shape dies having one or more angularly related locating surfaces to which a restoring force can be applied to remove distortion. If the die is of ring shape, the bore group of surface portions 11a may be of any desired contour as long as they are generally coaxial with the peripheral group of surface portions 11b. However, the cylindrical construction is preferred so that the segments 35 will apply to the bore of the die ring 11 both an expanding force and an axial force to obtain the advantages mentioned heretofore. Also, when the die is made in the form of a ring, bore surface 11a may be threaded while peripheral surface 11b serves as a locating surface to provide the reverse of the illustrated construction. Also, other constructions beside the segments 35 may be readily used to achieve the purpose if they apply a radially expanding force to eliminate radial distortion and an axial force to eliminateaxial distortion while providing an axial locating surface to provide the coplanar alignment.

Various changes in details and arrangement of parts can be made by one skilled in the art without departing from either the spirit of this invention or the scope of the appended claim.

What I claim is:

A ring die and mounting combination for a rotary planetary rolling machine capable of utilizing warped or eccentrically related ring dies, comprising a machine spindle rotatable about an axis and having a hub having an outer periphery about the axis and a flange presenting a precise planar surface adjacent said hub and at right angles to said axis, a ring die encircling said hub in spaced relation thereto, said ring die having inner and outer peripheral walls and end walls joining said peripheral walls, the outer peripheral wall having spaced form rolling zones, each zone including forming means extending circumferentially around said outer wall, each forming means having precise form rolling relationship throughout its extent with one end wall of said die, at least three arcuate wedge means equally spaced around said hub interposed between said hub and die, each wedge means having an inner surface engaging the outer surface of said hub and an outer surface engaging the inner surface of said ring die, one surface of said wedge means and its engaging surface being tapered longitudinally of said spindle and in a direction to create an expanding force on said ring die as said wedge means are moved toward said spindle flange, and means individual to each Wedge means for diiferential advancement of each Wedge means and corresponding portions of said ring die toward said spindle flange to force said one end wall of said die into tight coplanar engagement with said precise surface of said flange and cooperatively to relatively expand said 7 ring die in any areas creating eccentricity of the forming means with respect to said axis, said means thereby forcing said ring die into proper operating relationship and holding said die in such relationship for a rolling operation.

References Cited in the file of this patent UNITED STATES PATENTS Wilson et a1. Mar. 25, 1884 Clark et a1 Oct. 7, 1884 Wennersten Nov. 6, 1900 Batchelder Jan. 19, 1954 FOREIGN PATENTS i Canada Apr. 1, 1952 

